Oracle 练习用（2）

-- 1. sequence excisecreate sequence myseq start with 1 increment by 1 order cache 20 nocycle;select myseq.nextval from dual; -- currvaldrop sequence myseq;-- 2. Synonymsselect * from dual;select table_name from all_tables where lower(table_name) = 'dual';select table_name from user_tables;create public synonym USER_INFO for admin.USER_INFO;drop public synonym USER_INFO;-- 3. procedurecreate or replace procedure myprocasi number;begini := 100;dbms_output.put_line('i='||i);end;/exec myproc;drop procedure myproc;-- 4. triggercreate or replace trigger tr_USER_INFObefore insert or update or delete on USER_INFObeginraise_application_error(-20001,'can t modify');end;/delete from USER_INFO;drop trigger tr_USER_INFO;-- 5. back up & recovery-- a) imp & exp-- b) sql loader

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